Non-linear characteristic curves of electronic components are particularly disadvantageous in cases where the components are to be used for measuring purposes. If, for instance, a thermistor is used for measuring temperatures by measuring the voltage drop occuring at the thermistor when a specified current is supplied to it, it will be noted that the voltage drop decreases exponentially as the temperature rises. If this voltage is fed to an analogous measuring instrument and if one calibrates the scale in temperature units, a non-linear scale division will be obtained. When a digital indication of the temperature is desired, the thermistor curve must be linearized by a suitable circuit. Heretofore, the linearization of the exponential curve was achieved by the use of resistor networks, i.e. the exponential function was approximated via a rational function. However, such approximation is possible only over a very limited temperature range and that with decreasing accuracy.